A few months back jQuery was updated to version 1.4, with lots of new features and improvements. Yep, jQuery is now even more indispensable, and with more functions, methods and arguments to try and learn and remember.
It doesn’t matter how experienced you are, or how much you may use jQuery, trying to remember all of the jQuery functions is impossible.We all need a handy and reliable reference to refresh the memory and guide us.

Below you will not only find complete jQuery API cheatsheets for 1.4 (there are also links to previous jQuery releases), you will also find more specialized sheets for jQuery UI and Effects, jQuery CSS, jQuery Selectors, jQuery mobile development and even Validator cheatsheets. And on top of all that, you will also find the official jQuery references, docs and browsers as well as third party alternatives.

Official jQuery Docs and References

Version 1.4 – jQuery API Changes Documentation »
Many of the most popular and commonly used jQuery methods have seen a significant rewrite in jQuery 1.4, this documentation gives a detailed and comprehensive overview of these changes.

jQuery API – Official Documentation »
This a complete redesign of the previous API site and a complete rewrite. Every single method has been rewritten from the bottom-up to provide the best possible information about how jQuery works.
jQuery Core API Official Browser »
Visual jQuery 1.3 Browser »

Alternative jQuery Docs and Browsers

jQAPI – Alternative jQuery Documentation (HTML, AIR and ZIP)

The content of this browser is the exact same as in the official documentation, only with a fixed interface, better navigation and a lot easier when searching for a function. It ahs been completely inspired by the Rails API and desperate for a better navigation

jQuery API – Alternative Browser (HTML)

This jQuery API browser, updated for 1.4, is a complete rebuild of the official API browser (see above). Entirely driven by JavaScript, this resource has been designed to make it easier to quickly jump to any method either by searching or just to check the params.

jQuery Cheat-Sheets

jQuery 1.4 Cheat Sheet – Impulse Studios Labs (PDF)

This cheetsheet attempts to better align with the new documentation structure that jQuery is now using and clearly marks all new and updated functions for jQuery 1.4.

jQuery 1.4 API Cheat Sheet – Future Colors (PDF, HTML and PNG)

jQuery CSS Cheat Sheet (PDF)

jQuery – Select Element Cheat Sheet (PDF)

jQuery Selectors – Refcardz (PDF)

jQuery Selectors Cheatsheet (HTML)

jTouch Cheatsheet – Color Charge (HTML)

jQuery Validator Cheatsheet – Elegant Code (PDF)

jQuery UI 1.7 Cheatsheet (HTML)

jQuery UI – Effects Cheatsheet (HTML)

jQuery – YUI3 Rosetta Stone (HTML)

Previous jQuery Versions

jQuery 1.1. Cheat Sheet (PDF, PNG and XLS)

jQuery 1.2 Cheatsheet Wallpaper (1280×960)

jQuery 1.2 Cheat Sheet – gscottolson.com (PDF)

jQuery 1.3 Visual Cheat Sheet – Woorkup (PDF and JPEG)

jQuery 1.3 Cheatsheet – A Coding Fool (PDF)

jQuery 1.3 Cheatsheet Wallpaper (1920×1200, 1680×1050 and 1440×900)

jQuery 1.3 Cheatsheet (HTML)

jQuery 1.3.2 Cheat Sheet (PDF, PNG and Microsoft XLS)